Robi
Voiced by: Jim Meskimen
A robot butler who becomes acquainted with Shaggy and Scooby at the start of the series.
- Cloudcuckoolander: His programming isn't perfect, so he often has bizarre habits. One example is beginning Spring cleaning by removing and washing all of the screws and nails in the house, including the ones that are holding him together.
- Literal-Minded: Because of his faulty programming, he doesn't have a very good understanding of figures of speech. One example is in "Party Arty", where Shaggy and Scooby tell him to lie low and keep cool, which he interprets as an instruction to lie down as low as possible and cover himself with ice cubes. The same episode has him make shoestring fries by deep-frying shoelaces.
- Robot Buddy: He is a robot and Shaggy and Scooby's main companion for this series.
Albert Shaggleford
Voiced by: Casey Kasem
Shaggy's maternal uncle, who mysteriously disappears and leaves Shaggy with a large fortune and the formula for Scooby Snacks that give Scooby super powers.
- Cool Uncle: If an uncle who leaves his nephew with a vast fortune and a formula for Scooby Snacks that give his nephew's dog super powers isn't cool, who knows what is?
- Mr. Exposition: He moves the plot forward in every episode by explaining what the villain Dr. Phibes is up to.
- Sdrawkcab Alias: Dr. Trebla turns out to be him in disguise, with Trebla being his first name spelled backwards.
- Walking Spoiler: It's hard to talk about him without mentioning his disguise.
Dr. Phineus Phibes
Voiced by: Jeff Bennett
The main villain of the series. A mad scientist who plans to gain immortality and take over the world, goals he'd easily achieve were it not for the hippie boy and doggy who keep meddling in his affairs.
- Artificial Limbs: He has a swiss army weapon for a hand.
- Bald of Evil: Downplayed in that he has a comb-over that just barely covers up his scalp. Played completely straight with his clone Evil Phibes, who doesn't have any hair on his head and boasts being even more evil than the original.
- Big Bad: He's the main villain of this show and holds the distinction of being the first ever main villain in a Scooby-Doo series when earlier entries relied on the Monster of the Week format.
- Butt-Monkey: He tends to suffer humiliating misfortunes throughout the series. Heck, a lab accident he suffered years ago has made it so that for the first season he can't go outdoors without getting struck by lightning regardless of the weather.
- Expy: Producer Eric Randomski described Phibes as "Col. Klink plus Dr. Evil divided by Strangelove".
- Fear of Thunder: Very much so justified, as a freak lab accident turned him into a living lightning rod, even when it isn't the right weather.
- Immortality Seeker: He frequently expresses his desire to become immortal.
- Mad Scientist: He's a mad scientist.
- Must Have Caffeine: He's very picky about his hot mocha lattes.
- Screams Like a Little Girl: Especially whenever lightning is involved. After all, he is voiced by the same guy who voiced Johnny Bravo.
- Surrounded by Idiots: With the exception of Dr. Trebla, Dr. Phibes doesn't really think much of any of his henchmen's intelligence and gets infuriated whenever they bungle things up.
- Uncertain Doom: While trying to escape in the Grand Finale via jet pack, Shaggy rips off a cord from his jet pack and he spins uncontrollably, leaving his fate uncertain.
Agents 1 and 2
Voiced by: Jim Meskimen (Agent 1), Jeff Bennett (Agent 2)
The two most frequently appearing minions of Dr. Phibes.
- Bumbling Henchmen Duo: They are frequently seen together.
- Butt-Monkey: They don't have any luck with dealing with Shaggy and Scooby. Agent 1 gets the worst of it, having to put up with such a moron like Agent 2.
- The Ditz: Agent 2 is a complete idiot, much to his assistant and Phibes' chagrin.
- Dope Slap: Agent 2's buffoonery often earns him this courtesy of Agent 1, sometimes under the command of Phibes.
- Fat and Skinny: Agent 1 is tall and skinny while Agent 2 is shorter and pudgier.
- Fat Idiot: Agent 2 is obese and the least intelligent of Dr. Phibes' minions.
- Fat Comic Relief: Agent 2 is overweight and provides a lot of the comedy.
- Hypercompetent Sidekick: Agent 1 is arguably more competent than Phibes himself.
- Literal-Minded: Agent 2, of course. He once literally cracked open a window in Phibes' underwater lair.
- Not-So-Harmless Villain: Despite their butt monkey status, Agents 1 and 2 are a genuine threat on occasion. In the first episode, while suffering humiliations, they still managed to successfully capture Shaggy and Scooby.
- Screams Like a Little Girl: They both scream like this when Robi shoots them in the first episode.
Dr. Trebla
Voiced by: Scott Menville
A scientist who is often at Dr. Phibes' side. It turns out that he's really Shaggy's Uncle Albert in disguise.
- Affably Evil: He's always kindly consoling Phibes about the failure of his plans while display gin a sense of sorrow and awe at stuff like the rain forrest Phibes plans to destroy. Of course he isn't really evil.
- Cast as a Mask: His true identity is Shaggy's Uncle Albert, who is voiced by Casey Kasem rather than Scott Menville.
- Gonk: He's rather ugly and unattractive. It's later shown to just be a mask worn by Shaggy's Uncle Albert.
- The Mole: He's really Albert Shaggleford and was pretending to be on Phibes' side to bring down his operations from the inside.
- Satellite Character: There isn't much to him other than being a scientist working for Phibes.
- Walking Spoiler: It's hard to talk about him without mentioning his true identity.
Agents 3-13
Ricky and Mark
Voiced by: Jim Meskimen (Ricky), Jeff Bennett (Mark)
Ricky
Mark
Dr. Phineus Phibes's techies.
Chef Francoise
Voiced by: S. Scott Bullock
The world-class chef hired by Shaggy and Scooby.
Menace
Voiced by: Frank Welker
- Yellow Eyes of Sneakiness: Menace has yellow sclerae around his black iris.
